1. Field of the Invention
The current invention is in the field of polymeric films used to improve the properties of other materials.
2. Description of the Related Art
Protective films can be applied to other materials or articles for many reasons. Protection of an article is one reason to cover the article with a protective film. Different types of protection are possible, including protection from corrosion, protection from ultra-violet (UV) radiation, physical protection, gas permeation, and thermal control. Different materials and/or different additives can be used to provide the different types of protection, and it is possible to use multi-layer protective films to increase the amount of protection or the types of protection provided. Polymers are often used in protective films for their strength and flexibility. A wide variety of properties can be obtained by selecting the proper polymer, additives to the polymer, and additional layers or coatings of a polymer.
For example, certain articles can be protected from ultra-violet [UV] radiation damage with an exterior polymeric layer which reflects or absorbs the UV radiation. Most of the UV radiation is prevented from reaching the underlying article, so UV damage to the article is reduced. Protective films can also provide protection from ozone, atomic oxygen, or other corrosive environments. Additionally, it is possible for a polymeric layer to increase the rate of emission of electromagnetic radiation without increasing the rate of absorption of electromagnetic radiation, so radiant heating can be controlled.
In many applications, the weight of an article should be minimized. For example, many aerospace applications require articles to be as lightweight as possible to facilitate flight. One example of an aerospace application which benefits from lightweight articles is an airship that remains aloft because it is lighter than air. One method to reduce the weight of an article is to minimize the thickness of a necessary protective film without significantly increasing the density of the film. Airships often have a significant surface area which requires a protective film, so reducing the thickness of the protective film can significantly reduce the weight of the entire airship.
Protective films can be independently produced, and then applied to an article. Techniques to produce thin protective films with the ability to adjust the protective properties are desirable, because the protective films can be used on many different applications. However, in many embodiments the protective film should be relatively long and/or wide, because application of multiple small protective films is labor intensive and uneconomical. Thin films can be difficult to manage, because thinner films tend to be weaker and more susceptible to damage than thicker films. It is easier to produce and manipulate very thin films in relatively small pieces, because manipulation of larger sheets can require larger forces to position and support the larger surface area. However, covering a large surface area with small sections of film is not practical. For example, it would be very labor intensive and difficult to cover the surface of a large airship with sections of film that measure 25 centimeters by 25 centimeters.